As well-known to the trade, in the previous vehicular rearview mirror, when an adjustment of its reflection angle is required, the driver of the vehicle must move out of the driving seat and shift the reflection angle by hand through visual measurement to a direction he thinks suitable. Then he will return to the driving seat and check the suitability of the angle; if the angle is not suitable, the mirror must be adjusted once more; in order to adjust the reflection angle of rearview mirror to an accurate, proper direction, the driver must move out of and into the driving seat to repeatedly adjust said rearview mirror several times to achieve the end. In the case of the rearview mirror being fitted at the left and right sides of the driving seat, such as on buses, cargo trucks and vehicles provided with a shifting button, although the driver can remain at his seat and adjust by hand the rearview mirror adjacent to his position to a proper reflection angle, as for the rearview mirror at the other side, he must move out of his seat to make adjustments; again, he must adjust it repeatedly several times to arrive at a proper reflection angle. It is not only troublesome, but also takes time and effort.